Systematic profiling of SH3-mediated Tau-Partner interaction network in Alzheimer's disease by integrating in silico analysis and in vitro assay.

The aberrant assembly of microtubule-associated protein Tau (τ) into insoluble aggregates is closely related to Alzheimer's disease (AD), which is elicited from Tau phosphorylation events and regulated by the specific intermolecular recognition between the proline-rich PxxP motifs of Tau and the SH3 domains of its diverse partner proteins/kinases. Here, we attempt to create a systematic interaction profile for the 10 SH3 domains of previously reported Tau partners across all the 18 Tau PxxP peptides. A number of biologically functional SH3-PxxP interaction events are identified from the profile and then tested using fluorescence spectroscopy. It is revealed that (i) the region (residues 520-560) precedent to the tubulin-binding partial repeats of Tau protein is an important target of SH3 domains, where contains the three PxxP peptides τp527-536, τp530-539 and τp547-556 that exhibit different binding profiles towards the investigated SH3 domains, (ii) as compared to τp527-536 and τp547-556, the τp530-539 peptide located between them has only a modest binding potency to most SH3 domains, suggesting that the three peptides contribute unevenly to Tau-SH3 interactions, and (iii) some other Tau PxxP peptides, particularly those within the residue range 490-510 that is neighboring to the region 520-560, can also interact effectively with several SH3 domains. The SH3 domain of the well known Tau partner kinase Fyn is determined to have high or moderate affinity for an array of Tau PxxP peptides, including τp137-146, τp493-502, τp527-536 and τp547-556 (Kd ranges 15.7-85.6 μM).